This is a request for supplemental funds for committee travel and for the conduct of special histo-pathology studies on tissue obtained from patients entered on Intergroup Rhabdomyosarcoma Study (IRS) I and II. IRS I and II, collaborative efforts of Cancer and Leukemia Group B, Children's Cancer Study Group, and Southwest Oncology Group, are multi-disciplinary studies designed to answer important questions about the treatment and biological characteristics of rhabdomyosarcoma (RMS) in childhood and adolescence. Special pathology studies are to be conducted retrospectively on the tissues obtained from the more than 800 patients entered on IRS-I (November 21, 1972 - October 31, 1978) and prospectively on tissues from patients to be enterAd on IRS-II (activated November 1, 1978). The systematic cyto-histologic review developed and successfully applied in the National Wilm's Tumor Study will be applied to IRS histologic materials with the major goals being to 1) identify histo-cytologic features of pretreatment tumors that are of prognostic significance; and 2) identify distinctive sub-types of RMS and describe their features and patterns of spread; and 3) derive a staging system. Additionally, the value of electron microscopy and tissue culture techniques in diagnosis and elucidation of the tumor biology will be explored. Studies will also focus on Extraosseus Ewing's tumor and necropsy material.